Newbie Question

• To: mathgroup at smc.vnet.net
• Subject: [mg32686] Newbie Question
• From: "Brunsman, Kenneth J" <kbrunsman at ou.edu>
• Date: Wed, 6 Feb 2002 03:41:43 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Hello Group,

I can't believe that I am asking this question, but ... I'm tired of Fortran
and find the symbolic part of Mathematica extremely useful.

I have a list with Dimensions = {10,000, 6} and I need to find the Percent
Difference between items in a column.

I can parse out the column I need using Take [data [[All, Column #]]] --- no
big deal.  So far, so good.

Now here's the problem --- How do I get % Differences between any of 10,000
items in that list?  I need to take % Differences between adjacent pairs,
i.e. n and n-1, as well as items n and n-m where m can range from 1 to
10,000.

Further, I need to make sure that this code runs fast because I'm about to
run this on a data set of 10^8 data points (financial times series).  I
could do this standing on my head in Fortran, but I'm bound and determined
to learn Mathematica if it takes the rest of my unnatural life.

This is my first time attempting list processing and all I'm doing is
screwing up royally.

Help is greatly appreciated.

Best to all,

Ken Brunsman

University of Oklahoma
Michael F. Price College of Business
Division of Management
307 W. Brooks, Room 205
Norman, OK  73019-4006

405.325-5689

```

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